The invention relates to a device for spraying coating product and, more specifically, to a device comprising at least one spraying device capable of selectively spraying different products on objects to be coated.
It is known to use a device called a unit for changing coating product or xe2x80x9ccolour changing unitxe2x80x9d to supply one or more devices for spraying coating product from different lines each connected to a tank of coating product.
An installation is known from EP-A-0 274 322, in which a multi-axis robot bears a tank of coating product connected to a spraying device and allowing it to be supplied with product from connection means provided at a fixed station in a booth. Furthermore, WO-A99/52644 discloses a process and an installation for spraying coating product, in which a station for cleaning-filling a tank, borne by a multi-axis robot and associated with a spraying device, is disposed in a booth, this station comprising a product changing unit connected to supply circuits and a carrousel of tanks for the least used shades.
DE-A-42 14 779 discloses a manual device for changing colours in which an alignment between a downstream pipe and a plurality of upstream pipes is obtained by rotation of a deck. Controlled valves must be provided both upstream and downstream of this device, these valves having to be manoeuvred by hand or being constituted by electro-valves whose cost price is high.
The known systems therefore generally comprise a large number of controlled valves or electro-valves and numerous pipes and pneumatic connections for theses valves, which increases their cost price and renders the cleaning operations more complex insofar as these valves must be cleaned with considerable care in order to avoid a mixture of the coating products detrimental to a spraying of quality as required, in particular, in the domain of automobile vehicle construction.
U.S. Pat. No 3,240,225 discloses an apparatus for selecting paint in which paint pipe inlets are arranged in a circle, which imposes movements of considerable amplitude on the connection device which is associated therewith. This results in the compulsory use of relatively long supple pipes which must be drained and cleaned each time the product is changed, hence a relatively great consumption of paint and solvent. In addition, the circular movements imposed on the mobile members are long, hence a relatively long minimum cycle time for a paint changing operation.
It is a more particular object of the invention to overcome these drawbacks by proposing an installation comprising a reliable and economical coating product changing system while remaining easy to clean.
In that spirit, the invention relates to a device for spraying coating product comprising at least one spraying device and a plurality of lines for supplying this spraying device with coating product linked to a connecting assembly, in which each downstream end of a supply line is provided with a gate valve which can be controlled by a controlled actuator positioned at the entrance to a supply pipe for the spraying device, this actuator and this assembly being adapted to be displaced in relation to each other in such a way that the actuator can be selectively positioned opposite a downstream end of one of the supply lines and can manoeuvre the valve of that line. This device is characterized in that the ends of the lines are arranged in rows and in columns while an assembly comprising the actuator and connected to the supply pipe is mobile parallel to a plane surface of this plate where the line ends open out.
Thanks to the invention, one sole actuator is used for the selective connection of a plurality of supply lines with the spraying device and/or a tank associated therewith. It is therefore not necessary to provide a large number of actuators, such as electro-valves, as is the case in the prior art systems. The valves housed in the downstream ends of the supply lines are controlled by the actuator only when the latter is correctly positioned with respect to the corresponding end, with the result that there is no risk of accidental opening when the connecting assembly and the supply pipe are not correctly positoned in relation to each other. The risks of leakage of coating product are therefore minimized and the installation is xe2x80x9canti-dripxe2x80x9d by nature. Moreover, the device of the invention is substantially more compact than those of the state of the art while the angular position of the supply lines, on the one hand, and of the supply pipe, on the other hand, are compatible with a high-speed flow of the coating product. The ends of the supply lines and the supply pipe are easy to clean, which allows a saving of coating product during product changes. Finally, due to the arrangement of the line ends in rows and columns, it is possible to displace the assembly comprising the actuator freely in two directions perpendicular to each other and parallel to the plane surface. This facilitates selection of the coating product to be sprayed.
According to advantageous but non-obligatory aspects of the invention, the device incorporates one or more of the following characteristics:
the valve of each supply line end comprises a means for elastically returning into closed position, the actuator being adapted to open this valve against these return means.
the actuator is adapted to be partially engaged in each supply line end and comprises a part forming pusher adapted to displace a flap of the corresponding valve towards a position of opening of this valve.
the connecting assembly comprises means for supplying air and/or product for cleaning the pipe and/or the actuator, these means being continuously connected on the mobile assembly, by means of supple tubes.
According to a first advantageous embodiment of the invention, the actuator comprises a tubular sleeve adapted to penetrate in the gate valve of the supply line end and inside which is disposed a flap for closure of the pipe, this sleeve being adapted to immobilize the mobile assembly with respect to the plate by cooperation of shapes. In this way, the downstream end of the supply line and the pipe are obturated as soon as the actuator is spaced apart from the connecting assembly.
According to another embodiment of the invention, the actuator comprises a pneumatically controlled pusher mobile in translation in a chamber formed in a body fast with the spraying device and comprising a tank for storing coating product. This corresponds to the case of a tank borne at the end of the arm of a robot as described in EP-A-0 274 322 and WOA-99/52644. The body advantageously comprises means for connecting the chamber to a source of air and/or of cleaning product.